The central questions in any mystery are “who is the killer/villain?” and “what is the motive?” The answer may surprise you.

I’ve just started reading the book “Evil: Inside Human Violence and Cruelty” by Roy Baumeister. He’s a college professor who examines the question not from a theological or moral standpoint, but the perspective of psychology and sociology.

In the first couple of chapters I’ve found some interesting ideas. First, all persons have the capacity to do evil, only most choose not to do through self-control.

I’ladd my own theory that this self-control is often enforced through religious teaching (“thou shalt not kill”) and the law (“life in prison without parole”).

Nearly everyone has felt intense anger at some point most manage not to give in to their feelings. Road rage begins with two people letting their self-control slip so they can act on their fury until the incident ends in injury or death.

Baumeister says most people know their killer and few murders are committed by strangers.

He also says most murderers—and I would add sex criminals—are ordinary folk, both in their lifestyle and appearance. They don’t have hideous faces, evil grins, wicked laughs or gang banger attitudes to indicate their evil intensions.

Such persons are often charismatic, charming and even likeable, which is how they lure in their victims. Who would suspect such a nice person to be capable of a monstrous deed?

Criminals didn’t see themselves as doing wrong. The killer says the person deserved it. A rapist may blame alcohol or drugs, not his free own choice. The rapist will say the victim “enjoyed it” or “I couldn’t help it,” a complete denial of reality.

Victims tend to preserve the memory of the crime (which is why some can engage in revenge killings year later) whereas criminals will downplay the incident or push it out of mind: “let bygones be bygones.” To them, the act is over and done with; let’s move on.

A cozy mystery fits with these observations. The murderer is always local and known, sometime a long-time pillar of the community. No serial criminals or strangers here.

The identification of the killer is a surprise because it’s the person who seems least likely to do it, while the red herrings have more obvious motives.

The murderer sees the killing as justified: it had to be done.

“Columbo” was such a clever show because the killers were smart, attractive, suave, friendly and often well respected in their professional. On the surface they led orderly lives without even a parking ticket on their record.

Yet they found themselves trapped in a situation that they thought would harm them and they saw no other recourse than to eliminate the problem.

Columbo’s skill was that he understood human nature. Beneath the veneer of the model citizen beat a killer’s heart.

It’ll be interesting to read more of the book and see how the author’s observations can be applied to writing mysteries.